1. Field of the Invention
The invention relates generally to axle/suspension systems and, in particular, to the suspension assemblies of those systems, which are useful for heavy-duty vehicles such as trucks and tractor-trailers. More particularly, the invention is directed to a heavy-duty trailing or leading arm rigid beam-type suspension assembly for trucks and tractor-trailers, in which the beams securely and efficiently capture the axle. More specifically, the invention is directed to an improved axle seat bracket-to-beam connection, which generally includes a pair of transversely aligned and spaced-apart weld stops attached to and/or formed on the beam of the suspension assembly adjacent the axle seat bracket. These weld stops serve as guides for starting and/or stopping the welds between the beam and the axle seat bracket and provide for a more robust axle seat bracket-to-beam connection, resulting in improved durability of the axle/suspension system.
2. Background Art
The use of air-ride trailing and leading arm rigid beam-type axle/suspension systems has been very popular in the heavy-duty truck and tractor-trailer industry for many years. Air-ride trailing and leading arm spring beam-type axle/suspension systems also are often used in the industry. Although such axle/suspension systems can be found in widely varying structural forms, in general their structure is similar in that each system typically includes a pair of suspension assemblies. In some heavy-duty vehicles, the suspension assemblies are connected directly to the primary frame of the vehicle. In other heavy-duty vehicles, the primary frame of the vehicle supports a subframe, and the suspension assemblies connect directly to the subframe. For those heavy-duty vehicles that support a subframe, the subframe can be non-moveable or moveable, the latter being commonly referred to as a slider box, slider subframe, slider undercarriage, or secondary slider frame. For the purpose of convenience and clarity, reference herein will be made to a slider box, with the understanding that such reference is by way of example, and that the present invention applies to heavy-duty vehicle axle/suspension systems suspended from primary frames, moveable subframes, and non-movable subframes.
Specifically, each suspension assembly of an axle/suspension system includes a longitudinally extending elongated beam. Each beam is located adjacent to and below a respective one of a pair of spaced-apart longitudinally extending main members of the slider box. More specifically, each beam is pivotally connected at one of its ends to a hanger, which in turn is attached to and depends from a respective one of the main members of the vehicle. An axle extends transversely between and typically is connected by some means to the beams of the pair of suspension assemblies at a selected location from about the mid-point of each beam to the end of the beam opposite from its pivotal connection end. The opposite end of each beam also is connected to a bellows air spring or its equivalent, which in turn is connected to a respective one of the frame main members. A brake assembly and shock absorber also are mounted on each of the beams and/or axle. A height control valve is mounted on the hanger and is operatively connected to the beam in order to maintain the ride height of the vehicle. The beam may extend rearwardly or frontwardly from the pivotal connection relative to the front of the vehicle, thus defining what are typically referred to as trailing arm or leading arm axle/suspension systems, respectively. However, for purposes of the description contained herein, it is understood that the term “trailing arm” will encompass beams, which extend either rearwardly or frontwardly with respect to the front end of the vehicle.
The beam on which the axle is mounted is typically either a top-mount/overslung beam or a bottom-mount/underslung beam. An axle is mounted on the top of and is supported by the bottom-mount/underslung beam-type, with generally an upper portion of the axle being exposed. Conversely, an axle is mounted on the bottom of a top-mount/overslung beam, with generally a lower portion of the axle being exposed. Axle-to-beam mounts are typically fortified in some manner to maintain the mount integrity and prevent separation of the axle from the beams. Such fortification usually includes additional mounting hardware such as U-bolts, U-bolt brackets, and the like, resulting in a secure axle-to-beam connection more capable of withstanding operational loads.
More particularly, the axle seat typically is formed in each beam by nesting a front axle seat bracket into a pair of transversely-aligned grooves formed in the opposing sidewalls of the beam adjacent the front edge of the aligned arches formed in the beam sidewalls. A rear axle seat bracket is nested into a pair of transversely-aligned grooves formed in opposing sidewalls of the beam adjacent the rear edge of the aligned arches formed in the beam sidewalls. The front axle seat bracket is rigidly attached to the beam via welds laid along the edge of the axle seat bracket and the first top plate of the beam. The rear axle seat bracket is rigidly attached to the beam via welds laid along the edge of the axle seat bracket and the second top plate of the beam. In this manner, the front and rear axle seat brackets along with the aligned arches formed in the sidewalls of the beam form an axle locus for placement of the axle.
The welded connections of the axle seat brackets to the beam are subjected to high stresses during operation of the heavy-duty vehicle. These stresses can be especially pronounced for extreme-duty vehicles, such as those that are rated at about 30,000 lbs. per axle or more. Under these conditions, the welded connection of the front axle seat bracket can potentially become compromised or become weakened during vehicle operation, resulting in reduced durability of the axle seat bracket-to-beam connection and, in turn, reducing the durability of the axle-to-beam connection of the axle/suspension system.
Therefore, a need exists in the art for an improved axle seat bracket-to beam connection for axle/suspension systems, which utilizes a pair of weld stops located adjacent to the axle seat bracket-to-beam connection to fortify the axle seat bracket-to-beam connection. The welds stops provide both a start and a stop point for welding the axle seat bracket to the beam, thereby providing a more robust axle seat bracket-to-beam connection, resulting in improved overall durability of the axle/suspension system.